Where F is the future value of the investment (=$29,000), P the principal (=$24,000), r is the interest rate per compound period (unknown in our case) and n is the number of compounding periods (2*4=8).

Therefore, (using solver or graph) and then multiply this number by 4 and get the interest rate per annum

The guidelines for doing this exercise directly to GDC Casio FX-9860 is

TVM -> F2: Compound Interest -> PV=24000, FV=-29000, P/Y=4, C/Y=4, n=8 and then press I% and get the same result (9.57%).